Experimental Study on Cement-slag-titanium Gypsum-electrolithic Slag Compliant Curing of Dredged Silt

Soft soil curing has long been a scientifically and technically challenging subject. In order to solve the problems of insufficient early strength of cement-cured soft soils and the high resource, minimization and environmental costs associated with the use of cement, the development of cementitious curing agents with a "low carbon footprint" based on industrial solid waste instead of ordinary silicate cement is essential. This concept is also considered as a greener approach for the development of soft soil curing. In this study, slag and titanium gypsum were used as curing agents to partially replace cement in the treatment of dredged mud. The effects of curing agent dosage, slag-titanium gypsum ratio and alkaline exciter dosage on the strength of cured soil at different ages were mainly investigated. Unconfined compressive strength (UCS), scanning electron microscope (SEM) and X-ray energy spectrum analysis (EDS) tests were conducted. The results showed that the amount of curing agent mix, slag-gypsum ratio, and alkaline exciter content had a decisive effect on the UCS of cured silt. The optimum mixing ratio was 25% cement dosing, 55:10 slag-titanium gypsum ratio, and 10% alkaline exciter content. Scanning electron microscopy (SEM) demonstrated that the uniformly distributed gel-like products formed in the cured silt were tightly bound to the soil particles. In addition, EDS analysis confirmed that the gelatinous products were mainly composed of C-S-H gels and calcium-based aluminum silicates (C-A-S-H), and the needle-and-rod products were calcite.